June 2001

Top Ten Public Works Projects of the Century

Editor's Note: APWA developed the Top Ten Public Works Projects of the Century Program to honor the ten most outstanding public works projects of the 20th Century that significantly affected and improved the quality of life in the United States or Canada. Our goal was to generate awareness of the positive contributions public works has made as well as to build appreciation for public works and its contributions to North America.

The APWA Reporter will highlight each of the outstanding projects through the October 2001 issue. This issue features the Hyperion Treatment Plant.

The Hyperion Treatment Plant

Managing Agency: City of Los Angeles, California, Department of Public Works

Nominated by: City of Los Angeles, California, Bureau of Engineering

November 23, 1998 is considered by many Southern Californians as the most important day in the history of healing Santa Monica Bay. On this day, the City of Los Angeles' Hyperion Treatment Plant operated at full secondary treatment capacity for the first time in nearly half a century. This achievement assured the four million residents of Los Angeles and millions of more neighbors and visitors that the world-renowned Santa Monica Bay would be protected from wastewater pollution for future generations.

In the late 1800s, wastewater from the small Pueblo de Nuestra Senora la Reina de Los Angeles was conveyed from the center of town through natural waterways to the ocean. In 1892, the City purchased 200 acres of oceanfront property and, from 1894 until 1925, raw sewage was discharged into near-shore ocean waters at Hyperion's future location. In response to objections from swimmers and visitors to Santa Monica to raw sewage in their bathing waters in 1925, the City of Los Angeles built and started operating the first treatment facility at the Hyperion site: a simple screening plant.

During World War II, several miles of beach in front of the plant were quarantined because of near-shore discharge of what was still essentially raw sewage. After the war, plans for a full secondary treatment plant at the Hyperion site were developed, eventually funded, and built. When the new Hyperion Treatment Plant opened in 1950, it included full secondary treatment processes and biosolids processing to produce a heat-dried fertilizer. It was among the first in the world to capitalize on the energy values of biogas by operating anaerobic digesters, which have yielded a fuel gas by-product for over 50 years. At the time, Hyperion was the first large secondary treatment plant on the West Coast, and one of the most modern facilities in the world.

At that point in our history, the population of Los Angeles exploded. To keep up with growth and the resultant higher flows, treatment levels were cut back to enable Hyperion's operators to process the rising volume of wastewater using the available facilities. By 1957, the new plant was discharging a blend of secondary and primary effluent through a five-mile ocean outfall. Hyperion then stopped its biosolids-to-fertilizer program and began discharging digested sludge into the Bay through a separate seven-mile ocean outfall.

Discharging 25 million pounds of wastewater solids per month began to take its toll on the marine life in Santa Monica Bay. Samples of the ocean floor where sludge had been discharged for 30 years demonstrated that the only living creatures were worms and a hardy species of clam. The City of Los Angeles launched the Sludge-out to Full Secondary program in 1980. The $1.4 billion construction program replaced nearly every 1950-vintage wastewater processing system at Hyperion while the plant continuously treated 350 mgd and met all NPDES permit requirements.

This massive effort meant the end of spills at Hyperion; a 95 percent reduction in the amount of wastewater solids going into Santa Monica Bay; the elimination of the Bay's ecological dead-zone near the mouth of the sludge outfall; vast improvements in biological integrity of the bottom-dwelling marine community; remarkable increases in the relative abundance of many indicator-species; and partnerships among the public, regulatory agencies, government, and dischargers that led to one of the great environmental achievements of the 20th Century: the Hyperion Story-from "Sludge-Out" to full secondary treatment.